The invention relates to a valve timing gear for an internal combustion engine and, more particularly, to a lubrication arrangement therefor.
The valve timing gear of internal combustion engines must be supplied with lubricant, generally, oil. This is particularly true for the contact area between the valve bridge piece and the valve stem end. However, access to this region is sometimes difficult. This is particularly true of multivalve cylinder heads and, in that context, especiaily of a V-type engine, wherein the valves are arranged in a 45.degree. inclined position.
DE 33 30 141 C2 describes a valve timing gear for an internal combustion engine,wherein a lubricant passage with a calibration means or restractor is provided in the camshaft. The purpose of this lubricant passage is to provide lubricant to a rocker arm for actuating a valve. However, the lubricant passage can lead to weakening and wear of the camshaft, so that this way of lubricating the valve rocker arm is not suitable in practice.
German Offlegungsschrift 3,515,850 discloses a valve-actuating arrangement for an internal combustion engine with an overhead camshaft or camshafts. In this arrangement, an acnuating device, designed as a pivot arm, actuates a pair of exhaust valves in each of the cylinders of the internal combustion engine. All the valve actuating elements are lubricated by way of a main oil supply passage which running through a tubular pivot arm support shaft which has passages extending to the parts which move relative to one another, and outflow openings which are aligned with these parts. this arrangement, appropriate side passages with outflow openings are also provided in the actuating devices.
The disadvantage of the valve actuating arrangement disclosed in DOS 3,515,850, however, is that it is very complex and the side passages are located in moving components, making it difficult to control the flow of the lubricant properly.
It is the object of the present invention to provide a valve timing gear with which it is possible to achieve selective lubrication, particularly in the form of drip feed oiling in a simple manner, even for valves to which access is difficult.